How are meridians calculated?

According to the formula of "A gallbladder, B liver, C small intestine, D heart, E stomach and spleen, G large intestine, pungent lung, and any bladder and kidney", we can know that the representative of each viscera is one-day dryness. In these ten days, when the representative heavenly stems of meridians are consistent with the representative heavenly stems of heaven, it is said that this day is the meridian duty. When the day is dry, the gallbladder is on duty, and when the day is dry, the liver is on duty, and so on. However, each meridian tropism has its own time period, from the beginning of meridian tropism, to the sun drying up and seeing Sanjiao again, which is the time period of meridian tropism.